Ana’s rains flooded Sand Island Wastewater Treatment Plant

Hurricane Ana’s steady rain soaked Oahu Saturday through Sunday and disrupted the system at the Sand Island Wastewater Treatment Plant. The plant processes 60 million to 70 million gallons of wastewater on an average day. It’s equipped to handle twice that, but not what Ana poured down.

“Then it started spiking up, spiking up, spiking up. It went up to 240 million gallons,” Honolulu Mayor Kirk Caldwell said.

That overloaded the system and sent 5,000 gallons of partially treated wastewater into Honolulu Harbor. But 20 million gallons went into the treatment plant’s storeroom

“Twenty million gallons of sewage up to a couple inches of the tops of doors,” Caldwell said. “Somewhere between 6 and 8 feet of sewage down in this area where all of our electrical panels are.”

The flood short circuited electrical panels that operate the plant’s eight sewage clarifiers. Sand Island can still treat wastewater but can’t send sludge from the sewage to a processing plant until electricity is restored..

“They’re working very hard to get these two primary clarifiers up and running again. They anticipate having it up and running by Thursday if not sooner,” Caldwell said.

He said the treatment plant can function with just three clarifiers.

“We’ve learned that in future rain events we’re going to make sure that any holes and overflows are dealt with and temporarily sealed,” Caldwell said.

He said Ana has prompted his administration to develop a standard operating procedure for future rain events.